Control of Multiple Magnetic Micro Robots

2015 ◽  
Author(s):  
Denise Wong ◽  
Jeremy Wang ◽  
Edward Steager ◽  
Vijay Kumar
Keyword(s):  
Magnetic Field ◽  
Linear System ◽  
Applied Field ◽  
Dimensional System ◽  
One Dimensional ◽  
Electromagnetic Coils ◽  
Micro Robot ◽  
Simulation Results ◽  
Visual Feedback Control ◽  
The Magnetic Field

A magnetic micro robot is a microscopic magnet that is controlled by a system of electromagnetic coils that generate a magnetic field to manipulate the magnetic robot. A major challenge for manipulating multiple magnets at microscale is that the applied field affects the entire workspace, making it difficult to address individual magnets. In this paper, we propose a system where electromagnetic coils are close to the magnets being manipulated to exploit spatial non-uniformities in the magnetic field. Our model considers the magnetic field generated by the electromagnetic coils and the magnetic fields present from neighboring magnetic robots to generate the desired force on each magnet. This approach is demonstrated on a macroscopic, one-dimensional system with two magnets controlled by two electromagnets using visual feedback control. Additionally, simulation results for a linear system with three magnets and three electromagnets are shown. While demonstrated at the macroscale, our results suggest that our methods can be extended for microscale manipulation, where it is advantageous to control multiple identical magnets with global fields.

scholarly journals The influence of resistivity gradients on shock conditions for a Petschek reconnection geometry

2016 ◽  
Vol 34 (4) ◽  
pp. 421-425
Author(s):  
Christian Nabert ◽  
Karl-Heinz Glassmeier
Keyword(s):  
Magnetic Field ◽  
Necessary Conditions ◽  
The Other ◽  
Diffusion Region ◽  
Two Dimensional ◽  
Characteristic Velocity ◽  
Magnetohydrodynamic Equations ◽  
One Dimensional ◽  
The Magnetic Field ◽  
Alfven Velocity

Abstract. Shock waves can strongly influence magnetic reconnection as seen by the slow shocks attached to the diffusion region in Petschek reconnection. We derive necessary conditions for such shocks in a nonuniform resistive magnetohydrodynamic plasma and discuss them with respect to the slow shocks in Petschek reconnection. Expressions for the spatial variation of the velocity and the magnetic field are derived by rearranging terms of the resistive magnetohydrodynamic equations without solving them. These expressions contain removable singularities if the flow velocity of the plasma equals a certain characteristic velocity depending on the other flow quantities. Such a singularity can be related to the strong spatial variations across a shock. In contrast to the analysis of Rankine–Hugoniot relations, the investigation of these singularities allows us to take the finite resistivity into account. Starting from considering perpendicular shocks in a simplified one-dimensional geometry to introduce the approach, shock conditions for a more general two-dimensional situation are derived. Then the latter relations are limited to an incompressible plasma to consider the subcritical slow shocks of Petschek reconnection. A gradient of the resistivity significantly modifies the characteristic velocity of wave propagation. The corresponding relations show that a gradient of the resistivity can lower the characteristic Alfvén velocity to an effective Alfvén velocity. This can strongly impact the conditions for shocks in a Petschek reconnection geometry.

Electromagnetic damping of elastic waves: Experimental results

1968 ◽  
Vol 5 (4) ◽  
pp. 825-829 ◽  
Author(s):  
F. E. M. Lilley ◽  
C. M. Carmichael
Keyword(s):  
Magnetic Field ◽  
Elastic Wave ◽  
Applied Magnetic Field ◽  
Elastic Waves ◽  
Applied Field ◽  
Eddy Currents ◽  
Electrical Conductor ◽  
Electromagnetic Damping ◽  
The Waves ◽  
The Magnetic Field

The passage of an elastic wave causes straining and translation in the transmitting material. If a magnetic field is applied, and the medium is an electrical conductor, some of the energy of the wave is dissipated by the flow of electrical eddy currents. Usually the amount of energy lost is very small, but it may be greatly increased if the applied field is strongly non-uniform.Laboratory experiments are described which demonstrate this effect for standing elastic waves in a metal bar. The applied magnetic field changes from almost zero to its full strength over a distance which is short compared to the length of the standing wave. The result of this strong non-uniformity is that the energy lost due to the translation of the bar in the field greatly exceeds the energy lost due to the straining of the bar in the field.The dependence of the attenuation of the waves by the magnetic field is investigated for variation in frequency of vibration, bar thickness, and field gradient.

Design of a Dynamic Magnetic Field Steered Cathodic Arc Source in Arc Ion Plating

2011 ◽  
Vol 340 ◽  
pp. 167-172 ◽  
Author(s):  
Wen Chang Lang
Keyword(s):  
Magnetic Field ◽  
Cathode Surface ◽  
Target Surface ◽  
Target Thickness ◽  
Current Ratio ◽  
Operating Modes ◽  
Electromagnetic Coils ◽  
Cathodic Arc ◽  
Dynamic Magnetic Field ◽  
The Magnetic Field

In this work, a dynamic arched magnetic field steered arc source was deigned by virtue of Finite Element Method (FEM) calculation. The magnetic field was produced by two main electromagnetic coils so that the magnetic field can be adjusted with the help of the two currentI1and I2,whereI1is the current to the internal coil mounted coaxially in a magnetic yoke generating a static arched magnetic field to confine the cathode spots and I2is the current to the external coil mounted coaxially outside the above yoke adjusting the position of the vertex of arch. Base on the results of simulation, it was found this design enable the sweeping of the arc spots on the target surface by means of adjusting the ratio of current (I1/I2) , and cause the arc distribute evenly on the cathode surface in the diffuse arc mode transferred from the constricted arc mode. The effects of the target thickness and current ratio on the configuration and intensity of dynamic arched magnetic field were investigated. The optimized operating modes was proposed and discussed.

Effects of Magnetic Fields on PN Junctions in Piezomagnetic–Piezoelectric Semiconductor Composite Fibers

2020 ◽  
Vol 12 (08) ◽  
pp. 2050085
Author(s):  
Chao Liang ◽  
Chunli Zhang ◽  
Weiqiu Chen ◽  
Jiashi Yang
Keyword(s):  
Magnetic Field ◽  
Composite Fiber ◽  
Transverse Magnetic ◽  
Piezoelectric Semiconductor ◽  
One Dimensional ◽  
Current Voltage ◽  
Potential Applications ◽  
Multiferroic Composite ◽  
The Magnetic Field ◽  
Current Voltage Relation

We study the electromechanical and electrical behaviors of a PN junction in a multiferroic composite fiber, consisting of a piezoelectric semiconductor (PS) layer between two piezomagnetic (PM) layers, under a transverse magnetic field. Based on the derived one-dimensional model for multiferroic composite semiconductor structures, we obtain the linear analytical solution for the built-in potential and electric field in the junction when there is no applied voltage between the two ends of the fiber. When a bias voltage is applied over the two ends of the fiber, a nonlinear numerical analysis is performed for the current–voltage relation. Both a homogeneous junction with a uniform PS layer and a heterogeneous junction with two different PSs on different sides of the junctions are studied. It is found that overall the homogeneous junction is essentially unaffected by the magnetic field, and the heterojunction is sensitive to the magnetic field with potential applications in piezotronics.

Travelling fronts in nonlocal models for phase separation in an external field

1997 ◽  
Vol 127 (4) ◽  
pp. 823-835 ◽  
Author(s):  
Enza Orlandi ◽  
Livio Triolo
Keyword(s):  
Magnetic Field ◽  
Metastable Phase ◽  
Glauber Dynamics ◽  
One Dimensional ◽  
Kac Potentials ◽  
Nonlocal Models ◽  
Nonlocal Evolution Equation ◽  
Travelling Fronts ◽  
The One ◽  
The Magnetic Field

We consider the one-dimensional, nonlocal, evolution equation derived by De Masi et al. (1995) for Ising systems with Glauber dynamics, Kac potentials and magnetic field. We prove the existence of travelling fronts, their uniqueness modulo translations among the monotone profiles and their linear stability for all the admissible values of the magnetic field for which the underlying spin system exhibits a stable and metastable phase.

Hysteresis of the Resonance Absorption in Y–Ba–Cu–O

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3292-3295
Author(s):  
Gy. Kovács ◽  
N. Khatiasvili ◽  
T. Porjesz ◽  
I. Vajda
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Applied Field ◽  
Resonance Absorption ◽  
High Frequency Field ◽  
Hysteretic Behaviour ◽  
Frequency Field ◽  
The Magnetic Field

The effect of weak d.c. magnetic field on the interaction between high–T c superconductors and high frequency field has been studied. The magnetic field (Bres) at which the most intensive change in the absorption could be obtained depended on the previously applied field and displayed a hysteretic behaviour but it did not depend on the frequency.

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